Process for feeding a gas-consuming unit

Abstract

A gas-consuming unit (HF) is fed partially by a flow delivered directly by a compression unit (21) and partially by one delivered by a separation apparatus (25) which is itself fed by a flow delivered directly by the compression unit. Another flow produced by the separation apparatus, but at lower pressure, is returned to a compression unit before being sent to the consumer unit.

What is claimed is: 
     
       1. Process for feeding a gas-consuming unit (HF), in which: i) a feed flow consisting of a gas mixture is compressed in a compression unit (21);   ii) a first part (28) of the compressed mixture is sent to the gas-consuming unit (HF);   iii) a second part (23) of the compressed mixture is sent to a separation apparatus (25) which separates the mixture to produce two gas flows, one of which is at a higher pressure than the other;   iv) the gas flow (24) at higher pressure is sent to the gas-consuming unit (HF);   (v) the other gas flow at a lower pressure (26) is sent for compression to at least said compression unit (21), and the gas thus compressed is sent to at least one gas-consuming unit (HF, HF2, HF3); and   (vi) the feed flow is air and said two gas flows are both enriched with the same one of nitrogen or oxygen.   
     
     
       2. Process according to claim 1, in which the two gas flows are sent to the same gas-consuming unit (HF). 
     
     
       3. Process according to claim 1, in which the other gas flow at a lower pressure and the, or one of the, feed flows are compressed in the same compression unit (21). 
     
     
       4. Process according to claim 1, in which a gas-consuming unit (HF) is fed with at least two feed flows compressed separately by compression units consisting of respective blowers (21, 21A). 
     
     
       5. Process according to claim 4, in which a first blower (21A) is fed by the other gas flow (26), and a part (23) of the feed flow compressed in a second blower (21) is sent to the separation unit (25). 
     
     
       6. Process according to one of the preceding claims, in which the separation unit (25) is also fed with air delivered by an air compressor (41, 51). 
     
     
       7. Process according to claim 1, in which the gas at higher pressure is produced by the gas-consuming unit (25) by vaporization of a liquid in direct or indirect heat exchange, optionally with a compressed air flow. 
     
     
       8. Process according to claim 1, in which the gas at higher pressure is compressed for this pressure. 
     
     
       9. Process according to claim 1, in which the air or the gas at higher pressure is compressed by a compressor driven by an expansion turbine of the separation unit (25). 
     
     
       10. Process according to claim 1, in which the separation unit (25) is a cryogenic distillation unit. 
     
     
       11. Process according to claim 1, according to which the gas-consuming installation (HF) is a blast furnace which consumes oxygen-enriched air. 
     
     
       12. Installation for feeding a gas-consuming unit (HF), comprising: a compression unit (21), a gas-consuming unit, a unit (25) for separating a gas mixture,   a means for sending a gas mixture to the compression unit,   a means (22, 28) for sending a first part of the compressed mixture to the gas-consuming unit,   a means (23) for sending a second part of the compressed mixture to the separation unit (25),   a means (24) for sending a first gas, at higher pressure, from said separation unit to the gas-consuming unit (HF, HF1),   a means (36, 38) for sending a second gas from said separation unit to at least said compression unit (26, 38, 39) and subsequently to at least one gas-consuming unit (HF, HF2, HF3), wherein the first gas and the second gas are both enriched with the same one of oxygen and nitrogen.   
     
     
       13. The process of claim 1, wherein the gas flow at higher pressure is mixed with the first part of the compressed mixture prior to being received by the gas-consuming unit (HF).